Organophilic clays are used in oil-based drilling muds. To make such clays by one conventional method, the clay is first slurried at a low concentration in water. Dissolved amine activator is combined with the dilute clay slurry in a reaction tank. The reacted slurry is thereafter passed through a filter press, and the partially dewatered product is then flash-dried and hammer-milled. The above process is energy-intensive, especially in the flash-drying step.
In another known method, the clay is wetted to about 20% mositure with a water solution of the amine reagent. The resulting paste mixture is subjected to mechanical shearing action in a pug mill or extruder to cause ion exchange to take place. Following the milling action, the paste requires drying with the consequent added energy costs.